The present invention relates generally to structures, such as ramps, used to transfer a read/write head toward and away from a disc surface. More particularly, the invention relates to surface treatments of ramps used for loading and unloading heads in a data storage system, to reduce or eliminate erosion of the ramp surface.
Disc drives are used for storing information typically as magnetically encoded data, and more recently as optically encoded data, on a disc surface. The disc spins at high rotational velocities such that the head or slider flies above the disc surface on a cushion of air. The head generally includes a transducer or focusing device for reading or writing the data or for transmitting focused light between the disc and a transducer. A suspension arm is used for radially accessing different data tracks on the rotating discs.
Generally, all hard drive discs are tested before shipment. During a glide test, the glide head or slider files over a disc surface generally at a predetermined clearance from the disc surface, known as the glide height or fly height. If contact occurs between the glide head and a disc defect or asperity, forces on the glide head create responses that can be measured with transducers mounted on or near the head. A suspension arm is used to move the glide head to test different positions on the spinning disc.
The disc stops spinning when the disc drive is turned off. When the disc is no longer spinning, the head no Longer rides on a cushion of air. Contact between the disc surface and the head can result in data loss and in damage to the head arid disc. To reduce these risks, the head can be moved to a specially prepared portion of the disc surface where the surface is treated, for example, with a special texture, to reduce damage when contacted with the head. Generally, this portion of the disc is not used for data storage. However, this reduces the storage capacity of the disc.
In some disc drives, the head is moved away from the disc when the disc is no longer spinning. These operations of moving the head away from and back to the disc surface are referred to as unloading and loading the head, respectively. Dynamic loading and unloading is used to move a head onto or off of a disc surface using a ramp. Thus, the head can be safely positioned away from the disc when the disc stops spinning. In particular, the bead is removed from the vicinity of the disc surface when the disc is spun down and return when the disc resumes spinning.
Dynamic loading/unloading provides for an improved ability of the data storage system to withstand non-operating shock, a capability to achieve storage capacity improvements, improved surface stiction, improved durability, reduced start current requirements, and enhanced power saving modes operation. An improved ability to withstand shock results from having sliders/heads that are not parked on the surface of the disc such that slider impact on the disc surface is avoided. Since texturing of the disc surface is avoided by not resting the slider on a portion of a stopped disc, smoother disc and correspondingly reduced fly heights are possible. Power saving enhancements result from an ability to power down actuator electronics while the disc pack continued to spin.
Dynamic loading/unloading involves the guidance of the head away from the disc surface by gliding the actuator arm along a ramp. Generally, the arm supporting the head comes to rest on the ramp with the slider safely away from the disc surface. However, contact between the arm and the ramp can result in wear of the ramp. Ramps have been formed from polymer materials due to manufacturing considerations and cost. The suspension assembly for the head generally includes a stainless steel dimple or the like for contacting the ramp. The contact geometry between the suspension assembly and the flat ramp produces a relatively small contact area with a correspondingly large contact stress.
Repeated sliding of the suspension assembly over the ramp surface during load/unload operations can cause a wear track and a commensurate removal of polymer material from the ramp surface. As a result, debris is generated, which may deposit at the head/disc interface. In particular, debris can accumulate on the head or disc surface to prevent proper flight, leading to abrasive wear on the head and disc surfaces. It is well known that particles can cause severe wear and even crashing of the head onto the disc surface.
The present invention provides a reduction to the debris problem and offers other advantages over the prior art.
The present invention relates to a disc drive unit with a coated load/unload ramp that resists abrasion, which greatly reduces the above-mentioned debris problem.
In accordance with one embodiment of the invention, a disc drive unit includes an actuator assembly with a suspension assembly supporting a head and a ramp positioned to guide the head toward or away from a data storage surface. The head facilitates data transmission with respect to the data storage surface. The actuator assembly positions the head at selected locations along the data storage surface. The ramp surface preferably has a compound that includes carbon nitride or metal nitride, which may be in the form of a coating.
In accordance with another embodiment, the invention pertains to a method for applying a carbon nitride onto an organic polymer material. The method includes directing a nitrogen plasma at the surface of the organic polymer material, where the organic polymer material serves as a carbon source.
These and various other features and advantages which characterize the present invention will be apparent upon reading of the following detailed description and review of the associated drawings.